Hydraulic transmission



July 20,1926. 1,592,854 .W. E. MAGIE ETAL HYDRAULIC TRANSMISSION FiledAugusll 5, 1918 4 Sheets-Sheet 1 WIJ-"N555: MW %u7 l 4 ATTORNEYS.

July .20, 1926. 1,592,864

W. E. MAGIE ET AL HYDRAULIC TRANSMISSION Filed August 3, 1918 4Sheets-Sheet 2 INVENToRs.- M7/fuman! ie YJuly 20,1926. '1,592,8@4

W. E. MAGIE 'ET AL HYDRAUL; C TRANSMI SS ION Filed August 5, 1918 4Sheets-Sheet 3 o W NS w Hf Eg R A 7' TORN E YS.

IN VEN TORS.'

July zo 1926.

W. E. MAGIE ET AL HYDRAULIC TRANSMISSION Filed Augusi'l 3, 1918 4Sheets-Sheet 4 wnwrss:

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Patented July 20, 19,26.

UNITED STATES 1,592,864 PATENT OFFICE.

WILLIAM E. MAGIE, 0F BUFFALO, NEW YORK, AND WALTER FERRIS, UFMIL'WA'KEE, WISCONSIN, ASSIGNORS '10 THE OILGEAR COMYANY, OF MILWAUKEE,WISCONSIN',

nconlrom'rron or WISCONSIN,

HYDRAULIC TRANSMISSION.

Application nled August 3, 1918. SeriaLNo. 248,177.

This invention lrelates to variable speed hydraulic transmissions of thetype involving a multiple cylinder hydraulic motor connected through ahydraulic circuit with a multiple lc linder pump'so as to be driven byliquid elivered'by the pump.

` In .this type of variable speed ytransmissions the pump stroke isordinarily adjustable to vary the direction and rate of delivery ofdriving liquid' to the motor, so as to regulate the speed and directionof motin of the motor. Thev use of a motor whosestroke is alsoindependently adj ust-` able has been suggested but discarded as im--practical because of the serious complications and even dangerousconditions of-operation that have heretofore resulted from such use.Adjustment of the motor stroke causes a change not only in motor speedbut in motor torque as well. For instance, as the motor strokeapproaches zero the torque thereof approaches zero and under practicalworking condltlons the motor so adjusted 1s unable to use the liquidldischarged into the circuit by the pump. Dangerous excessive pressuresordinarily result. Furthermore lwith an independently adjustable pumpand motor the speed of the motor is uncertain because it is dependentupontwo independently variable factors, namely; the motor stroke and thepump stroke.

We have found however that it is frequently desirable, in the practicalapplication of hydraulic transmissions, to vary the torque of the motorin order to efficiently meet the varying demands of the driven machine.For instance, reciprocating machines such as planers, presses and thelike demand a relatively high torque at relatively low speed during theworking or feeding stroke, and a relatively low torque and high speedduring the return stroke. Further- 'more an accurate control 'of speedduring the working stroke is frequently desirable.

One object'of the present invention is the provision of a variable speedhydraulic transmission mechanism of the ty e mentioned which will permita desirab e variation in motor torque'and speed and' at the Sametimeavoid the objections heretofore' easy control of motor torque and speedis` thus assured. The relation of the pump and motor is also preferablysuch that the motor never assumes a zero stroke position, reversal ofthe motor being effected by reversing the pum Another object istheprovision of a variable speed transmission in` whichthe parts are soarranged as to avoid the necessity rfor adjustable or iiexibleconnections within the hydraulic power circuit.

Another object is the provision of novel `means for utilizing theworking pressures in the iiuid circuit to counteract and sustain thethrusts imposed upon the working parts. Other objects and advantageswill appear from the following description of an illustrative embodimentof the present invention.

In the accompanying drawings Figure 1 is a' longitudinal section throughthe machine along the line 1--1 of Figure 8; Figure 2 is a plan view inpartv section with cover removed;

Figure 3 is a section along the line 3--3 of Figure 1;

Figure #i is a detailed section along the line 4 4 of Figure 2;

Figure 5 is a plart section and part plan view of part of t e slidingpintle lock;

Figure 6 is a section on the line 6--6 of Figure 5.;

Figure 7 is a perspective of one of the cross head blocks;

Figure 8 is a perspective of one of the bearing collars;

Figures 9, 10, 11 and 12 are dlagrammatic views showing the relationbetween pintles and cylinder barrels under conditions of different s eedratios. y

Figure 13 1s a detailed section through a portion of one of thecross-head blocks.

Like arts are indicated by like letters in all the gures. e j

A is a main housi g having a removable cover A1. The hollow boss 2contains at its outer end an annular hydraulic bearing sleeve A3'i`nwhich is mounted for rotation a shaft A* carrying a pulley A adapted tobe driven from anyv` 'suitable source of power. This shaft A* I havetemed the pump shaft. It "carries on its inner end the pump driving'disc A, the hub A7 of which surrounds the end of the shaft A* and ismounted for rotation in a hydraulic pump bearing collar AB. the otherend of the machine contains a hydraulic bearing ring A1o in which isrotatably mounted the motor shaft A11 having a pulley A12. The inner endof this motor shaft carries the motor driving disc A13 the hub A14 ofwhich encloses the inner end of the shaft A11 and is rotatably mountedin a hydraulic motor bearing ring A15.

B is a sliding pintle block.' It has on either side outwardly extendingarms B1 B2 B3 terminating in guidel shoes B* which engage tracks B5 onthe inner wall of the housing A. This sliding pintle block is immersedat its lower end in oil which is contained in the bottom of the housingA. B6 is a controlling system extending upwardly from the sliding pintleblock. It terminates in a plunger B" slidable-in the cylinder BB in the.cover A1. B9 is a screw threaded in the upper end of the system andplunger adapted to be controlled by the operator through the hand WheelB10 to raise and lower the sliding pintle block.

C is a These pintles project out on opposite sides of the pintle block Band as shown are eccentric. They are both rigidly fixed on the block sothat a movement of the block moves the center of each pintle equallywith respect to the centers of the motor and pump shafts. C2 is a pumpcylinder barrel mounted upon the pintle C, C3 a motor cylinder barrelmounted for rotation upon the pintle C1. These two cylinder barrels areIdentical in every respect, the difference` in their motion being` dueto the fact that the pintles upon which they are mounted are on axeswhose eccentricity varies simultaneously and in the same or inversedirections. A discussion of one will, therefore, suffice for both andthe lungers, cylinders, bearings and associated) parts in connectionwith each of these two cylinder barrels and motor and pump driving discswill be identical.

Each of the cylinder barrels is made up of a series of radially disposedpump or motor cylinders D D. We have shown seven. There might be more orless. Preferably in order to get smoothness and uniformity in operation,it is best for reasons which experience has proven true, to provide anuneven number of cylinders. In each of these cylinders there is mountedfor reciprocation a plunger D1 provided at its upper end with alaterally extended bearing block or cross head D2 which bearing block orcross head is in slidable engagement with a fiattened surface D3 on theinner periphery of the collar D4 of the pump driving disc A6 or motordriving disc A13, and is The hollow boss A9 at' pump pintle and C1 amotor pintle.

gap between the ring D11 held against this surface at all times toprevent it dropping away when the pressure is released by lugs D5 D5extending outwardly from the face of the discs A6 A13 beneath and at oneside of the surface D3. We prefer to call these lugs and associatedsurfaces D3 a. cross head guide. They are exactly the same as the wellknown cross head guide used in connection with steam engine ports andthey hold the cross head in position so that they are free to slide butare held against withdrawal, and when the pintle is eccentric withrespect to the discs AG or A13 and if the device is rotated, the pistonswill move back and forth within the cylinders as each individual crosshead is moved toward and from its respective cylinder by their rotationabout different axes. De is a pressure duct extending longitudinallythroughoutthe entire length of the plunger D1 discharging at its upperend gto a pocket Dt in which is a coil spring the hydraulic cup D9apertured at its bottom so as to communicate with the pocket D7 andslidable in an enlarged pocket D1". This cup has an annular flangeextending out into the plane of the upper surface of the cross head D2and it is expected that it will beso seated in the pocket Ds that noappreciable oil leakage about the outer periphery of the cup between itand the cross head will take place but oil will be fed under pressurethrough the duct in the plunger, through the aperture in the bot-tom ofthe cup into the space between thc cup and the working surface of thecross head guide. Thus there will be a hydraulic pres sure exerted fromthe interior of each ycylinder directly against the working surface ofits crosshead guide, which will result in transmitting thrust betweenthe two relatively moving members with a minimum of mechanical friction..Y

In the modification shown in Figure 13 we substitute for the cup D1 aring D11 loosely mounted in the cross head held against the cross headguide by the cross bar D12 engaged by the spring Ds. This cross bar maytake any form. It might be a perforated disc or merely a perforatedplate as shown. Oil leakage around the ring is prevented by a leather orsimilar flexible packing strip D13 whirh bridges the and the wall of thecross head and ymakes it possible to dispense with any ground fit andits attendant expense and danger of binding.

It will be understood that the direction of rotation of the motor andpump cylinder barrels and their eccentricity control the direction offlow and the pressure of the working fluid in the main working system.

Each cylinder barrel then is mounted for. rotation on one of thepintles. The pump which spring presses upwardly against pintle isprovided With ports E E1 communicating respectively with ducts E2 E2, EsE3 on opposite sides of the pintle. l These ducts extend inwardly andcommunicate with the chambers E* E5 within the sliding pintle block.Similar ducts E0 E0 and E7 E7 lead from chambers E* E5 out throughthepintle C1 to communicate with ports E8 E0. These ports E E1 and E*3E9 are separated by partition walls E10 identical in both pintles. Thesepartition walls have outer cylindrical boundaries forming` a part of thebearing surface of the pintle and attention is called to Figure 6.wl1ereit will be noted that a rib E11 extends across at right angles to thepartition wall E10 but vterminates short of the periphery of the pintleso that the ports E8 E9 andE E1 are divided into -two separate pocketsand which, so far as` the operation of the device is concerned, have nofunction. They are formed by the wall E11 which is provided tostrengthen and stiften the pintle and provide a passage for the bleederducts used in connection with the reclaiming of the oil leakage. Eachof` thecylinders 'in both of the cylinder barrelsis provided with a portE12 adapted lto be in register with the ports E E1, Es E0. These portsare of such diameter lthat as the cylinder barrel rotates on the pintle,the broad working surface of the partition wall E10 cuts off onecylinder 'after another, forming a bridge the width of which is suchthat there can never be a by-pass between the ports E E1 and E E0 aroundthe cylinder wall E10 but each successive port and, therefore,

each successive cylinder will first be in communication with one of saidports, then out of communication with both, then in communication withthe other. It will be noted also that the ducts E2 E2, Es E1tare merelytwoseparate pipes in communication with each other. at each end throughthe central chambers!O and the ports.4 We might have substituted forthem one large passage but structurally two smaller ones are better.

Extending down from the chambers E* E5 are passages F, F1 controlled bygravity held ball valves F2 F3 which close the upper ends of thepassages F* F5 the lower ends of which are embedded in the oilreservoir. The ball valve arrangement is such that which ever one of thechambers contains iuid under positive pressure will .have its ball or'check valve seated, which ever one contains fluid under a negativepressure will open vits ball valve and by suction a ply. of motive fluidwill be drawn lu t rough the reservoir to completely l the svstemandreplace that motive fluid which leaksout.'

Extendin upwardly from the chambers E* E are ucts G G1 dischargingrespecf tively into the separated chambers G2 G3 .on the visible side inFigure l.

ladjacent the plu-nger B7. Leading from the chamber G1 G1. are pipes G*G1. These pipes extend down along the tracks B5 B5 and communicate withthe horizontally` disposed pipes G0 G7 respectively. The pipes G and G7communicate with the hydraulic bearing rings A8 and A15 on the lowerside thereof as shown in Figure 2 that is on that side which is cut awayin Figure 1. VCommunicating with these pipes G7 and extending up aroundthe bearing on the out-` side are pipes G8 GB. These pipes curve downaround the bearing and then pass through the housing Wall andcommunicate with the hydraulic bearing rings A3 A10 on the upper side ofFigure 2, that is on n the side shown in Figure 1. 'The pipes G0 G0communicate With the opposed sides of the hydraulic bearing rings A0A15, that is on the upper side shown in Figure 2 and Communicating withthese pipes where they join the bearing ring are pipes G9 G9 whichextend around beneath the bearings and then out through the wall of thecasing and communicate with the hydraulic bearing rings A3 A10 on theopposedvsides, that is on the lower sidein Figure 2 and on the sidewhich is eut away in Figure l. Attention is here called in general termsto the fact that when for instance the lower side of the pump lookingdown in Figure 2 is the pressure side, the pump barrel being fixed onthe pintle. will tend to force the member A6 down and that will beresisted bythe pressure on the lower side of the hydraulic ring. Thiswill tend to twist the pump shaft in a clockwise direction as you lookdown upon it and that will be resisted by pressure carried over to theopposed side of the hy draulic pressure bearing ring. The same situationprevails in connection with th pressure on the pump. t y

There are four hydraulic bearing rings A8, A8, A1l1 and A10. They varysomewhat in size but are identical so far 'as arrangement, function andshape is concerned. They consist in a collar havlng two substantiallysemicircular annular pockets. Figure 8 which shows one of them inperspective will suiiice for all.

Each one of these rings is made up of a cylindrical portion H havingopposed annular walls H1 `H2 to formtwo separate plressure pockets H3H*1 there being ports 5 H0 whereby the pressure pipes previouslydescribed may enter these pockets and lill them with the working iuidunder pressure. These pockets are separated by partitions H7which'divide the circumference of the collar into two substantiallyequal v'parts just slightly less than 1800 each. The

light load can be carried by'the edges of the two annular walls and bythe cross partitions that is when the pump or motor is the bearingrunning light without any load and there is no pressure in the systemthen the bearing pressures are caused merely by the weight of the partsand the pressure is so low that no special arrangement need be made tocarry them. When the machine begins to work ressures rise. At the sametime the hy raulic pressure rises and if we properly design the bearingsin the rst place no matter how great the bearing pressure becomes the.increase of the hydraulicpressure will just compensate for it and wewill have a hydraulic bearing at all times upon which the moving partsare always free to oat and if we change the direction of movement of theworking fluid and thus make what was once the pressure side now becomethe suction side and vice versa, it will be noted that the bea-ringloads will be reversed and so the reversal in pressures will-counterbalance the reversal in bearing loads and hydraulic bearing willcontinue to operate.

-It will be observed that. any leakage in operation between any of thedi lierent bearing parts will eventually tind its way into the reservoirin thebottom of the tank ir housing and will be replaced by suctioncaused by the absencel of pressure in one or the other of the centralchambers within the pintle block.

It will be evident that while I have shown in my drawings an operativedevice, still many changes might be made both in size, shape and arranement of parts without departing materia ly from the spirit of ourinvention and we wish, therefore, that our drawings be regarded as in asense diagrammatic.

The use and operation of our invention are as follows Referring first toFigures 9 to 12, it willhe understood that in each case the pump isrepresented b the o n line structure on the left side. he sli ing pintleblock is represented by the heavy black .structure and the motor by thelight line structure ou the right.

shown the `axes of rotation of pump and motor side fixed while thepintle block slides to change the axes of rotation of the motor and pumpcylinder barrels. Obviously, of course, itmight be possible andthe sameresult would be obtained if we made the ump and motor disc axesdifferent and ma e the pintles of the two barrels on the same line. Orwe might, have allfour of them oil' center and miht move the pintles ormove the motor and pump discs. The geometric and pumping result would bethe same. We have preferred, however, for the sake oi clearness toconfine ourselves-to the one form shown. It will be observed also thatthe pump always rotates in one direction as indicated by the arrow.'Starting with the In our present form we haveA situation of Figure 9,we find that the pintle block is so positioned that the pintle uponwhich the pump cylinder barrel rotates is concentric with the pumpdriving disc and so even though the pintle upon which the motor barrelis mounted is not concentric with the motor driving disc uo movement enthe motor side takes place because there 1s no reciprocating movement ofany of the pump pistons and n-o pumping is done.

In Figure 10, we show the sliding pintle block moved down so that itsaxes of rotation is say 1/8 inch off center. This gives a stroke of 1Ainch t'or each pump piston between extreme in and extreme out position.This adds to the eccentricity of the motor. Motive fluid is circulatedunder pressure and the pressure on the motor pistons causes them toreciprocate and causes rotation of the motor driving disc. But becausethe eccentricity of the pump is as shown here only l/g inch while theeccentricity of the motor is 11/3 Ainches the pump stroke being 1A inch,the motor stroke being 21A inches, the speed ot' the motor will be muchless than the speed ot' the pump and the torque of the motor will bevery high compared to the pump torque. In Figure 11, we have shown thesliding pintle block moved up so that the eccentricity is 1/8 inch inthe opposite direction. This reduces the eccentricity of the motor to'Mg inch. N ow the pump stroke is 1A of an inch but the motor stroke isonly 1% inches and the result of this is that the rotational speed ofthe motor more closely approaches that of the pump and the moto: 1sspeeded up at the expense of a slight reduction in torque.

InFigure 12, we have shown the sliding pintle block moved up so that thepum eccentricity is 5/8 inch, the stroke is 11A inc i and the motoreccentricity is only 3/8 inch. The motor stroke`is 1% inch or less thanthe pump stroke, therefore the motor travels at a much higher speed thanthe pump and with correspondingly reduced torque.

It will be observed vthat in Figs. 11 and 12 the direction of rotationof the motor has been reversed from what it was in the arrangement shownin Figure 10, because, of course, when we change the eccentricity of theump throu h an angle of 180 we make w at was at rst the ressure sidebecome the suction side and w at was the suction side becomes thepressure side and so that side of the motor system which before took oilunder pressure from the pressurev side of the pum now is exhaustin oilin the suction si e of thepump an the motor will -be reversed.

In connection with the hydraulic bearing system, attention is called tothe fact that whenV we change the pressure sides of the pump and makewhat was the pressure side now act as the suction side we make the sameaxis of rotation ofthe pump barrel is above 2, we will assume that thesliding pintle block is moved down so as to give the pump ltheeccentricity shownvin Figure 10. This makes the lower side as shown inFigure 2 the pressure side because as the pistons rotate in the downwarddirection the plungers are gradually forced into the cylinders exertingthe pressure and as they start up on the opposite side they are drawnout causing a suction. In the present instance then E1 is the port whichtakes the working fluid under pressure from the cylinders of the pumpcylinderbarrel. This working iuid travels through the passages E5 to thechamber E, thence through the passages E7 to the port E9 whence thefluid passes into the cylinders on the pressure side of the pump torotate it. As the cylinders pass one after another across the partitionwall between the pressure and suction ports they will discharge theiruid into the port E8 whence it passes back at low pressure through thepassage E, chamber E, passa e E2 and port E to ports E12 in the cylin'ers on the suction side of the ump. When this circulation is taking pace the position of the two ball valves in passages F and F1 will be asshown in Fig. 3.' The ball valveF will be seated preventing escape ofhigh pressure fluid, and valve Fz will be lifted, permitting workingfluid to be sucked up to replace that which leaks out at the differentbearings and units. o,

If on the other hand we raise up onjthe sliding pintlevblock withoutchanging -the direction of rotation of the pump so that the the axis ofrotation-l of the driving discwe have the istons gradually being thrustlinto the cylin ers on the'up stroke, that is on the right hand side ofFigure .4, and the motive iuid will rbe squeezed out -of these cylindersunder pressure in the passages E2 thence travelling to the `chamberE,'pas sages E and left 'hand side of the cylinder barrel in Figure 3to" cause arotation of the motor driving disc.

cause the motor driving disc to rotate in a counter clockwise directionbecause, of course, the pressure will tend to force the pistons out ofthe plungers and this can only `be done in company with the downwardmovement of each piston, cross head and cylinder. lAs rotation takesplace the working Huid having done its work w1ll `the respectivedistances This, nof course, will dischar into the passages Il7 where itwill travel t ence into the chamber E5 through the passages Es and besucked back into the motor on the suction side.

Of course, if the stroke is the same on both the motor and pump ends thedisplacement will be the same and the speed of rotation will be thesame. If the eccentricity and therefore the stroke of one is greaterthan the eccentricity and stroke of the other, then the displacement ofmotive fluid at each revolution of that member which has the greateststroke will be greater than the displacement of the other and thereforein the well known manner the member having the smaller displacement willmove at a relatively higher speed.

It will be noted as shown more clearly in Figure 3, that the twosystems, both the high and low pressure systems and they may be one orthe other because the high or low pressure systems are interchangeabledepending upon Vthe direction of rotation are to keep -it filled. Thecheck valves are provided, of course, to prevent escape of the iuidunder pressure from the pressure side while permitting ingress of fluidto the suction side. v

1.' In a hydraulic transmission, a pump comprising a revolving drivingpart and a revolving av revolving driving part and a revolving drivenpart, a shifting member carrying one of the revolving partsof the pumpand one of the motor, and means for traversing said member and therebysimultaneously varying between the axes of revolution of the tworevolving parts in the pump and in the motor.

2. In a hydraulic transmissioma pump and a motor each comprisingrotating driving and driven members, and cylinders and plun ers operatedby said rotating members and aving strokes dependent upon the distancebetween their axes of revolution, and a shifting member carrying onepart of the pump and one part of the motor whereby said strokes aresimultaneously changed:

3'. In a hydraulic transmission, a casing, a pump revolvin disc and vamotor revolving disc mounte therein for rotation about fixed aires, ashifting lmember mounted in the casing and carrying in relatively fixedpositions a pump cylinder barrelL and amotor cylinder barrel, the axesof revolution of the corresponding pairs of revolving discs and cylinderbarrels being so disposed that the shifting axis-of the pump mayv beplaced coincident with its corresponding fixed axis or upon either sidethereof while to the same hydraulic the shifting axis of motor remainson the same side of its corresponding fixed axis, thereby obtainingreversal of motor.

4. In a hydraulic'transmission a cylinder, a plunger closely fittedtherein, a plane driving surface abutting against the outer end of saidplunger, a cavity in the outer end of said plunger in communication withthe interior of the cylinder, whereby a thrust is communicated from saidcylinder to said plane driving surface, partially or entirely by directfluid pressure against the driving surface.

5. In a hydraulic transmission, a cylinder containing fluid underpressure, a plunger closely fitted therein and having a crosshead formedat its outer end abutting against a plane driving surface, a packingplate mortised into the outer end of the crosshead and having a cavityin its outer surface, and means for introducing into said cavity fluidunder pressure from within the cylinder.

6. In a hydraulic transmission, a pump or motor comprising a revolvingpart supported by a bearing a working fluid circuit having a highpressure and a low pressure branch, a pressure cavity in the contactsuria ce oi:' said bearing and means for transmlttmg the pressure in thehigh pressurebranch of the fluid circuit to the pressure cavity in saidbearing surface.

7. In a hydraulic transmissiona reversible pump or motor having arevolving part Supported by a bearing, a working Huid circuit connectedwith said pump or motor and having two branches carrying respectively ahigh and a low pressure and interchanging vtheir pressures upon reversalof p ump or motor, two pressure cavities in the caring connectedrespectivel with the two workin-g circuit branches an carrying themterchanging pressures therein, whereby hydraulic pressures in thebearing counteract the bearin reactions.

8. In a hy raulic transmission a reversile pump or motor having arevolving part supported by a bearing, cuit connected with said pump' or-motor and having two branches carrying respectively a high and lowpressure and interchanging their pressures upon reversal of pump ormotor, two pressure cavities in the bearing, said-cavities beingconnected respectively with the two branches of the working circuitactions in the bearing cavities are always proportional and inopposition to the mechanical reactions against said bearings dueressures acting in the pump or motor mec anism.

9. In a hydraulic transmission, a reversible pump or motor having arevolving part mounted in two bearings, a working iiuid clrcultconnected with said pump or motor and comprismg a high 'pressurel and alow a working Huid cir- ,d

whereby the hydraulic reh "mitting fluid from said pump .to said motor,

and means for adjusting said member to simultaneously vary thedisplacements of said pump and motor.

11. A hydraulic transmission comprising a pump and a motor anda closedworking circuit` connecting them means for simultaneously varying thedisplacement of both of them and changing the direction of iow of theworking fluid from the pump, said displacement varying Aand directionchanging means comprising a sliding block having means for supportingparts of said pump and motor, and means for sliding the block to changethe displacement of said pump and motor.

12. A hydraulic transmission comprising a pump and a motor and a closedworking circuit connecting them, meansfor changing both the speed andthe direction of the motor with respect to the pump, comprising meansfor varying the displacement of both pump and motor and for changing thedirection of the flow of working fluid from the pump, said displacementvarying and direction changing means comprising a sliding block havingmeans for rotatablysupporting parts of said pump and motor, and meansfor sliding the block.

13. In a hydraulic transmission the combination of a pump having aradial series of relatively reciprocating piston and cylinder elements,a motor havingl a radial series of relatively reciprocating piston andcyliner elements, a rigid member extending from the center of said pumpto the center of said motor vand formingr a. fluid conduit therebetween,and means for adjusting said member 'to vary the relative displacementsofsaid pump and motor.

v 14. In a hydraulic transmission the combination of a variable aving aseries of relatively reciprocating piston and cylinder elements, a motorhaving a series of relatively reciprocating piston and cylinderelements, a rigid member extending from said pump to said motor andforming a fluid conduit therebetween, and means for adjusting saidmember to vary the extent of reciprocation of the piston and cylinderelements of said pump.

15.- In a hydraulic transmission the combination of a pump having aseries of reladisplacement pump tively reciprocating piston and cylinderelements, a variable `displacement motor having a series of relativelyreciprocating iston ,and-cylinder elements, a rigid mem er extendingfrom said pump to said motor vand forming a fluid conduit therebetween,

and means for adjusting said member to vary the extent of reciprocationof the piston and cylinder elements of said motor.

16. In a hydraulic transmission the combination of a pump having aseries of relaf tively reciprocable piston and cylinder elementsradiating from a center, afmotorhavv ing a series4 of relativelyreciprocable piston and cyllnder elements radiating from a center, arigid member extendin 'from one center to the other, and means oradjusting. said member to vary the relative .displacements of said pumpand motor. `Signed at Bualo, New York, this 23rd day of July, 1918.

4 WILLIAM E. MAGIE. Signed at South Milwaukee, Wisconsin, this 15th dayof July 1918.

WAL'LER FERRIS.

